Background: Insulin resistance syndromes are a heterogeneous group of disorders with variable clinical phenotypes, associated with increased blood glucose and insulin levels. Case Presentation: Herein, a 10-year old girl with abnormal face and dentition is presented. She has suffered from diabetes mellitus type I since she was 6 years old. Hyperglycemia did not respond to age appropriate insulin dosage; therefore, insulin dosage was increased, but did not lead to appropriate glycemic control. Twenty two exons of insulin receptor gene (INSR), on short arm of chromosome 19, were sequenced, but no identifiable disease causing mutation was detected. Conclusion: Although a rare mutation within the intronic or promoter region has not been excluded in this case, further molecular studies on patients with insulin resistance syndromes associated with certain features are needed.